Real-time digital x-ray imaging apparatus

ABSTRACT

A x-ray diagnostic apparatus and methods perform Real-Time Digital Radiography with particular application in dental x-ray imaging modalities, such as Orthopantomography, Scannography, Linear Tomography and Cephalography, by using a versatile and robotized mechanical structure, featuring projection movements in the required a real range and automatic adaptation of the same mechanical structure to serve the various x-ray imaging modalities foreseen.

BACKGROUND OF THE INVENTION

Orthopantomography, Scannography, Linear Tomography and Cephalographyare complementary radiographic techniques, often combined in a singleequipment, of widespread use in dental radiology to obtain respectivelya comprehensive survey of the maxillo-facial complex, tomographic viewsof selected anatomical districts under transversal or axial projections,and cranial views under multiple projections, supporting the diagnosisin the dental prevention, restoration and follow up.

Orthopantomography aims to produce a radiographic image of a curvedplane approximating the patient jaws, with blurring of the anatomicalstructures laying outside a narrow layer around the predesignated curvedplane, by using the relative movement of the radiographic film versusthe rotation of the x-ray source to generate the layer forming effect.

Scannography has a layer forming process similar to Orthopantomography,where the object is typically laying on a flat plane. It is practicallyused to produce axial or transverse views of specific anatomicaldistricts, such as the jaw, the joints and the sinus.

Linear Tomography is an alternative technique, using the classic lineartomographic layer forming projection. It is practically used to produceaxial or transverse views of specific anatomical districts in the jaw.

Cephalography is a stationary radiographic technique, aiming to produceradiographic images of the cranial complex under various projections,with minimum magnification and geometrical distortion.

For all the indicated radiographic modalities the real-time digitalx-ray image acquisition is nowadays a more and more demanded feature. Itprovides instant image acquisition with reduced x-ray dosage, by takingadvantage of the improved performances and reduced costs provided by themodem image imager technology. It also allows safer and cleaneroperation, by removal of the film processing and related chemicals.

Both in conventional and digital modality, performing the radiographictechniques above typically requires a mechanical structure capable ofperforming orbital movements around the patient with simultaneoustranslation of the rotational centre.

A first difference is that in conventional Panoramic Radiography andScannography the x-ray film is simultaneously translated at a speed suchto obtain the blurring of the anatomical structures laying outside ofthe plane of interest, while in real time digital applications the x-rayfilm is replaced by the x-ray imager and special electronic techniquesare used to produce the same blurring effect.

A second difference is that in conventional Cephalography and LinearTomography a stationary x-ray film is used, while in real-time digitalapplications the stationary x-ray film can be replaced by a stationaryx-ray imager.

Alternatively, to significantly reduce the system cost, a linearlyshaped x-ray imager will be preferably used, and the image acquisitionwill be performed by using a horizontal or vertical scanning technique.

Another important difference is that, due to the high cost of the x-rayimager, in real-time digital applications it will be very desirable tohave an apparatus and method to relocate the x-ray imager, eithermanually or automatically, from the Panoramic to the Cephalographicposition.

The fundamental concept on which this invention is based was describedin prior art application (U.S. Pat. No. 4,985,907), where theroto-translatory system is disclosed realized by two independenttranslations movements in a plane and one independent rotation movementabout an axis perpendicular to that plane. The present invention furtherexpands this concept, by disclosing the new apparatuses and methodsrequired for the real-time digital implementation of the indicatedradiographic modalities.

Other prior art (U.S. Pat. No. 4,741,007) describes apparatus andmethods in which the roto-translatory movement is realised by means oftwo pivot shafts placed at a constant distance from each other, using aguide groove and an active actuator.

Further prior art (U.S. Pat. No. 5,012,501) describes apparatus andmethods in which a variety of orbital movements is produced by using afirst drive for the rotational movement, a second drive for the lineartranslation of the rotation centre, and a selector for selecting thedirection of the linear motion.

More recent prior art (WO 99/17659) describes apparatus and methods inwhich pivot shafts connecting multiple body parts are driven by activeactuators in a SCARA arrangement, allowing a variety of projectionmovements as required for various dental x-ray imaging modalities.

The concept of the three independent roto-translatory movementsdisclosed in prior art (U.S. Pat. No. 4,985,907) has proven itsflexibility in producing multiple orbital projections by simpleadjustment of the software programming data, and can be advantageouslyused for the generation of the orbital movements required forOrthopantomography, Scannography, and Linear Tomography, both inConventional and Real-Time Digital Radiography.

The main difference will be that in Real-Time Digital Radiography thefilm cassette with its independent drive is removed, and is replaced bythe x-ray imager having an active area of a size equivalent to the x-rayfield at the film plane as used in Conventional Radiography.

However, it will be the purpose of this invention to further exploit thebasic concept in order to implement the following desirable features:

-   -   Perform Real-Time Digital Cephalography by means of horizontal,        vertical or rotatory scanning movements, allowing at the same        time ergonomic and reproducible immobilisation of the patient by        suitable positioning system.    -   Perform automatic relocation of the x-ray imager between the        Panoramic and Cephalographic positions, in order to allow use of        the same imager in both imaging modalities.

SUMMARY OF THE INVENTION

The object of the invention is a x-ray apparatus providing a robotizedmechanical structure capable of performing Real-time Digital Radiographywith particular application in Orthopantomography, Scannography, LinearTomography and Cephalography.

In Real-Time Digital Orthopantomography, Scannography and LinearTomography the apparatus of the invention will be based on thefundamental robotic concept disclosed in U.S. Pat. No. 4,985,907, withthe difference that the film cassette with its independent drive will beremoved, and the x-ray imager will be introduced.

Various kinds of x-ray imagers will be allowed, and the active area ofthe x-ray imager will be of a size equivalent to the x-ray field at thefilm plane as used in Conventional Radiography.

In Real-Time Digital Cephalography a first approach may be to replacethe conventional radiographic film by a x-ray imager of equivalent size.

Also in this case various kinds of x-ray imagers used, based on existingtechnologies well known to those skilled in the art, such as CCD or CMOSor Amorphous Silicon readout devices optically coupled with scintillatorscreens or electrically coupled with direct x-ray detection screens.

This approach may become convenient in the future, but is very expensiveat the present status of technology and does not offer today an economicsolution for the dental practice application.

The alternative approach for Real-Time Digital Cephalography is toimplement the radiographic image acquisition by a scanning movement,either in the horizontal or vertical direction, or rotatory.

It will allow use of a linear shaped x-ray imager with reduced activearea, so offering a cost effective solution for the implementation ofthe Real-Time Digital Cephalography.

The robotic solution shall be usefully complemented by a mechanismperforming automatic relocation of the x-ray imager between thePanoramic and Cephalographic positions.

The purpose is to allow in a simple and effective way the use of thesame x-ray imager in all the foreseen imaging modalities, with evidentpositive impact on the overall system cost.

An innovative approach for Real-Time Digital Cephalography is alsoillustrated, where the same rotating arm conventionally used forpanoramic technique is translated according to a predefined path inorder to project from a virtual rotating centre the linear shaped sensorand build up, by using a geometric correction software algorithm, thecephalographic image acquisition by a scanning movement.

The invention is particularly advantageous in dental radiography, wherethe outlined features find immediate application, but it could also beadvantageously employed in other medical and non-medical applicationshaving similar requirements.

Here following is a description in greater detail of the invention,based on the exemplary embodiment illustrated in the attached drawings.

DESCRIPTION OF DRAWINGS AND TABLES

FIG. 1 is a diagram showing an exemplary system dedicated to dentalapplications.

FIG. 2 is a block diagram of the Cinematic Assembly system.

FIG. 3 is a schematic diagram of a control system for the presentinvention.

FIGS. 4, 4 a and 4 b are diagrams of different embodiments of thepresent invention substituting an x-ray imager for conventionalradiographic film.

FIGS. 5, 5 a, 5 b, 5C and 5D are diagrams of different embodiments ofthe present invention for horizontal scanning movement of the x-raysource and the primary x-ray collimator.

FIGS. 6, 6 a, 6 b, 6C and 6D are diagrams of different embodiments ofthe present invention for horizontal scanning movement of the primaryx-ray collimator.

FIGS. 7, 7 a, 7 b, and 7 c are diagrams of different embodiments of thepresent invention for vertical scanning movement of the x-ray source andthe primary x-ray collimator.

FIGS. 8, 8 a, and 8 b are diagrams of different embodiments of thepresent invention for vertical scanning movement of the primary x-raycollimator.

FIGS. 9, 9 a, 9 b, 9C and 9D are diagrams of different embodiments ofthe present invention for rotational scanning movement of the primaryx-ray collimator.

Wherever possible, the same reference numbers will be used throughoutthe drawings to refer to the same or like parts.

FIG. 10 is a diagram of an embodiment of the present inventionillustrating a detachable connector for the x-ray imager.

DETAILED DESCRIPTION

The system is a representative dental x-ray diagnostic system performingReal-time Digital Radiography in Orthopantomography, Scannography,Linear Tomography and Cephalography.

For those skilled in the art, it is intended that:

Orthopantomography is a narrow beam scanning technique aiming toreproduce in a single radiographic view the whole or part of a curveplane approximating the patient jaw, using layer forming methods bywhich the points laying in the target plane are reproduced on the samepoint of the radiographic image, while points laying outside the targetplane are blurred out.

Scannography is a narrow beam scanning technique aiming to reproduce ina single radiographic view the whole or part of a flat planeapproximating specific anatomical regions (such as the jaw, the joints,the sinus), using layer forming methods by which the points laying inthe target plane are reproduced on the same point of the radiographicimage, while points laying outside the target plane are blurred out.

Linear tomography is a wider beam radiographic technique, using theclassic linear tomographic layer forming projection, where by thecombined movement of x-ray source and x-ray imager around the object,only the points laying in the target plane are reproduced on the samepoint of the radiographic image, while points laying outside the targetplane are blurred out.

Cephalography is a stationary radiographic technique, where the cranialcomplex is exposed under various projections, with minimum magnificationand geometrical distortion.

The apparatus of the invention is based on the robotic concept alreadydisclosed in U.S. Pat. No. 4,985,907, with the difference that the filmcassette with its independent drive is removed, and the x-ray imager isintroduced.

Additionally it proposes various arrangements for performing Real-TimeDigital Cephalography either by a single large area x-ray imager, or byhorizontal, vertical or rotational scanning with a linear shaped x-rayimager.

Finally it describes suitable mechanisms for the automatic relocation ofthe x-ray imager from Panoramic to Cephalographic positions.

FIG. 1 illustrates the most general arrangement of the system and itsmain mechanical and electrical components.

The base 1 supports the whole apparatus. Frame 2 slides vertically alongthe base and is provided with an independent drive 2 a for the controlof the vertical movement. The vertical movement is used during patientpositioning, for the vertical adjustment to the patient height, and mayalso be used for vertical scanning in the relevant Cephalographicarrangement.

The rotary unit 3 is connected to the Frame 2 by the Cinematic Assembly4. It supports the x-ray source 11 at one end, and the x-ray imager 6 atthe other end.

The x-ray imager 6 is dedicated to the image acquisition in PanoramicRadiography, Scannography and Linear Tomography.

The x-ray source 11 provides the x-ray generation and includes the x-raytube and the focal spot from which the x-ray beam generates.

A primary x-ray collimator 5 is attached to the output port of the x-raysource 11, providing limitation of the radiation incident on the x-rayimagers.

Preferably the x-ray collimator will be of the motorised type, operatedby the independent active actuator 5 a under micro computer control.

The x-ray imager 7 is dedicated to the image acquisition inCephalography. It is rigidly attached, by an arm or the like, to theframe 2. Alternatively it may be attached to the rotary frame 3, in casethat the configurations adopting automatic sensor relocation as laterdescribed are used.

The x-ray imager is also provided with an independent active actuator 7a, to be used in configurations where the linear movement of the samex-ray imager is required during a scanning process, as later described.

A secondary x-ray collimator 8 is attached to frame 2. Alternatively itmay be attached to the rotary frame 3 or to an independent support, incases where configurations adopting automatic sensor relocation as laterdescribed are used.

It is provided with an actuator 8 a driving the movement of the samecollimator aligned with the x-ray beam during a scanning process undermicro computer control, as later described.

The actuator 8 a may be independent or mechanically controlled by theactuator 7 a of the x-ray imager.

A first patient positioning system 10 rigidly attached to the frame 2 isprovided for Panoramic Radiography, Scannography and Linear Tomography,while a second patient positioning system 9, also rigidly attached tothe frame 2, is provided for Cephalography.

In alternative arrangements, where the scanning process is used, thepatient positioning system 9 used in Cephalography may be independentlyattached either to the base frame 1, or to the floor, or to the wall,and be provided with an independent actuator, either active or not, forthe adjustment to the patient height.

In other alternative arrangements, where the automatic sensor relocationis used as explained later, the patient positioning system 9 used inCephalography may be attached to the rotary frame 3, and be providedwith an independent active actuator 9 a, allowing its repositioningrelative to its support frame in order to maintain a firm patientposition during a horizontal or vertical scanning process where themovement of the same support frame is involved.

FIG. 2 illustrates the detail of the Cinematic Assembly 4.

The Cinematic Assembly 4 implements the robotic concept, by providing 3independent axis for the rotation R, the X linear movement, and the Ylinear movement.

The X linear axis is composed by the motor drive 4 a rigidly connectedto the frame 2, and the linear bearing 4 b.

The Y linear axis is composed by the motor drive 4 c rigidly connectedto the support 4 d, and the linear bearing 4 e.

The R (rotation) axis is composed by the motor drive 4 f rigidlyconnected to the support 4 g, and the circular bearing 4 h.

The x-ray imagers 6 and 7 can be of various kinds according to the stateof the art.

The x-ray imager assembly construction will be based on existingtechnologies, and will typically consist of one or more sensor devices,each providing a detector modality, optically or electrically coupled toa readout device.

The detection modality can be a scintillating screen converting x-raysinto light, hence requiring optical coupling to the readout device, orit can be other direct detector materials (such as CdTe, CdZnTe,HPGe,HgI₂,GaAs,PbI₂) providing direct conversion of x-rays to electriccharge, hence requiring electrical bonding to the readout device pixels.

The readout layer is a semiconductor device whose fabrication is basedon various available technologies, among which CCD, CMOS or AmorphousSilicon, well known to those skilled in the art.

FIG. 3 shows a scheme for the control system for an apparatus accordingto the invention.

One or more microcontrollers 16 and associated memory 17 form the systemmicro computer, feeding the independent motor drives X,Y,R withcinematic profiles data associated to the specific orbital projection.

It also controls the actuator 7 a associated with the x-ray imager 7,the actuator 5 a associated with the primary x-ray collimator 5, theactuator 8 a associated with the secondary x-ray collimator 8, theactuator 9 a associated with the patient positioning system, and theactuator 2 a associated with the vertical slide of frame 2, for themovements required during the normal operation and during the variousscanning processes foreseen in Cephalography.

In FIG. 4, 4 a, 4 b arrangements are shown where the Real-Time DigitalCephalography is implemented by replacing the conventional radiographicfilm by a x-ray imager 7 of equivalent size.

In all the arrangements the primary x-ray collimator 5 is kept steady,and there is no secondary collimator.

In FIG. 4 is a first arrangement where the Cephalographic patientpositioning system 9 is supported on the same arm where the x-ray imageris suspended. The arm is rigidly connected to the frame 2.

In the alternative arrangements of FIG. 4 a, 4 b, a single large areax-ray imager can be relocated from Cephalography to PanoramicRadiography, Scannography and Linear Tomography. In this way the x-rayimager 7 takes the position and replaces the x-ray imager 6, soachieving a remarkable reduction of the system cost.

The extension movement of the apparatus may be automatically triggeredand controlled by a user command or by the selection of the radiographicmodality. It shall prevent collisions with the patient positioningsystem, and shall incorporate provision for safety release to avoidpotential injury to the patient.

In FIG. 4 a an arrangement is illustrated, where the x-ray imager 7 isrelocated from Cephalographic to Panoramic position and vice versa byusing a telescopic arm, either provided with an active actuator 12 or tobe manually actuated.

The Cephalographic patient positioning system 9 is supported on aseparate arm rigidly connected to the frame 2.

In FIG. 4 b another arrangement is illustrated, where the x-ray imager 7is relocated from Cephalographic to Panoramic position and vice versa byusing a folding arm, either provided with an active actuator 12 or to bemanually actuated.

The Cephalographic patient positioning system 9 is also supported on aseparate arm rigidly connected to the frame 2.

In FIG. 5, 5 a, 5 b, 5C, 5D arrangements are shown where the Real-TimeDigital Cephalography is implemented by a scanning process in thehorizontal direction achieved by a movement of the x-ray source 11,using a narrow x-ray beam and a linear shaped x-ray imager having anactive area of a length approximately corresponding to the minimumuseful height of the x-ray field size at the film plane used inConventional Cephalography.

In these arrangements software post-processing of the acquired imagewill be required to correct the magnification distortions in the Ydirection.

In FIG. 5 a first arrangement is illustrated where the x-ray source 11and the primary x-ray collimator 5 are simultaneously and linearly movedin the Y direction, by acting on the Y axis under microcomputer controlduring the scanning sequence.

The secondary x-ray collimator 8 and the x-ray imager 7 aresynchronously moved, aligned with the x-ray beam, by using therespective drive axis, 8 a and 7 a, under microcomputer control duringthe horizontal scanning sequence.

The Cephalographic patient positioning system 9 is supported on the samearm where the x-ray imager is suspended. The arm is rigidly connected tothe frame 2.

In this arrangement there are several other alternative movements of thex-ray source 11 which can advantageously used to realize the scanningprocess. By utilizing the roto-translating capabilities of the cinematicunit, the x-ray source 11 can perform a rotational movement around itsfocal point, otherwise it can move along a trajectory characterized inhaving a constant distance between the focal point and the x-ray sensor,otherwise more generally it can perform a projection from a predefinedvirtual centre of rotation.

Still referring to FIG. 5, arrangements are here following illustratedwhere the Real-Time Digital Cephalography is implemented by a scanningprocess in the horizontal direction achieved by a roto-translatingmovement of the x-ray source 11, using a narrow x-ray beam and the samelinear shaped x-ray imager 6 used for Panoramic Radiography,Scannography and Linear Tomography.

In such case the active area of the x-ray imager may require anadditional length in order to cover all the anatomical regions ofinterest.

In a first arrangement the rotary frame 3 performs a linear trajectoryin the Y direction, by acting on the Y axis under microcomputer controlduring the scanning sequence.

In other more complex arrangements, by utilizing the roto-translatingcapabilities of the cinematic unit, the rotary frame 3 can performroto-translating scanning trajectories where the object is illuminatedfrom a predefined virtual centre of irradiation among which thosedepicted in FIG. 5.

In all these arrangements software post-processing of the acquired imagewill be required to perform geometric correction of the magnificationdistortions.

In the alternative arrangements of FIG. 5 a, 5 b,5C, 5D, the x-rayimager 7 can be relocated from Cephalography to Panoramic Radiography,Scannography and Linear Tomography. In this way the x-ray imager 7 takesthe position and replaces the x-ray imager 6, so achieving a remarkablereduction of the system cost.

The extension movement of the apparatus may be automatically triggeredand controlled by a user command or by the selection of the radiographicmodality. It shall prevent collisions with the patient positioningsystem, and shall incorporate provision for safety release to avoidpotential injury to the patient.

In FIG. 5 a an arrangement is illustrated where the x-ray source 11, theprimary collimator 5, the secondary collimator 8, and the x-ray imager 7are simultaneously and linearly moved in the Y direction, by acting onthe Y axis under microcomputer control during the scanning sequence.

The Cephalographic patient positioning system 9 is supported on the samearm where the x-ray imager is suspended, while an independent activeactuator 9 ashall be foreseen providing movement relative to the supportarm in opposition to the scanning movement under microcomputer control,in order to maintain the patient in a firm position.

The x-ray imager 7 can be relocated from Cephalographic to Panoramicposition and vice versa by using a telescopic arm either provided withan active actuator 12 or to be manually actuated.

In FIG. 5 b an arrangement is illustrated where the x-ray source 11, theprimary collimator 5, the secondary collimator 8, and the x-ray imager 7are simultaneously and linearly moved in the Y direction, by acting onthe Y axis under microcomputer control during the scanning sequence.

The Cephalographic patient positioning system 9 is supported on the samearm where the x-ray imager is suspended, while an independent activeactuator 9 a shall be foreseen providing movement relative to thesupport arm in opposition to the scanning movement under microcomputercontrol, in order to maintain the patient in a firm position.

The x-ray imager 7 can be relocated from Cephalographic to Panoramicposition and vice versa by using a folding arm either provided with anactive actuator 12 or to be manually actuated.

In FIG. 5C an arrangement is illustrated where the x-ray source 11, theprimary collimator 5, and the x-ray imager 7 are simultaneously andlinearly moved in the Y direction, by acting on the Y axis undermicrocomputer control during the scanning sequence.

The secondary x-ray collimator 8 is synchronously moved by its actuator8 a and kept aligned with the x-ray beam under microcomputer controlduring the scanning process.

The Cephalographic patient positioning system 9 is kept steady duringthe scanning process, supported by an arm rigidly connected to the frame2.

The x-ray imager 7 can be relocated from Cephalographic to Panoramicposition and vice versa by using a telescopic arm either provided withan active actuator 12 or to be manually actuated.

In FIG. 5D an arrangement is illustrated where the x-ray source 11, theprimary collimator 5, and the x-ray imager 7 are moved linearly in the Ydirection, by acting on the Y axis under microcomputer control duringthe scanning sequence.

The secondary x-ray collimator 8 is synchronously moved by its actuator8 a and kept aligned with the x-ray beam under microcomputer controlduring the scanning process.

The Cephalographic patient positioning system 9 is kept steady duringthe scanning process, supported by an arm rigidly connected to the frame2.

The x-ray imager 7 is relocated from Cephalographic to Panoramicposition and vice versa by using a folding arm either provided with anactive actuator 12 or to be manually actuated.

In FIG. 6, 6 a, 6 b, 6C, 6D arrangements are shown where the Real-TimeDigital Cephalography is implemented by a scanning movement in thehorizontal direction of the primary x-ray collimator 5, using a narrowx-ray beam and a linear shaped x-ray imager having an active area of alength approximately corresponding to the minimum useful height of thex-ray field size at the film plane used in Conventional Cephalography.

In this case no software post-processing of the acquired image will berequired.

In FIG. 6 an arrangement is illustrated where the x-ray source 11 iskept steady, while the primary x-ray collimator 5, the secondary x-raycollimator 8 and the x-ray imager 7 are synchronously moved, alignedwith the x-ray beam, by using the respective drive axis undermicrocomputer control during the horizontal scanning sequence.

The Cephalographic patient positioning system 9 is supported on the samearm where the x-ray imager is suspended. The arm is rigidly connected tothe frame 2.

In the alternative arrangements of FIG. 6 a, 6 b, 6C, 6D, the x-rayimager 7 can be relocated from Cephalography to Panoramic Radiography,Scannography and Linear Tomography. In this way the x-ray imager 7 takesthe position and replaces the x-ray imager 6, so achieving a remarkablereduction of the system cost.

The extension movement of the apparatus may be automatically triggeredand controlled by a user command or by the selection of the radiographicmodality. It shall prevent collisions with the patient positioningsystem, and shall incorporate provision for safety release to avoidpotential injury to the patient.

In FIG. 6 a an arrangement is illustrated, where the x-ray source 11 iskept steady, while the primary x-ray collimator 5, the secondary x-raycollimator 8 and the x-ray imager 7 are synchronously moved, alignedwith the x-ray beam, by using the respective drive axis, 5 a, 8 a and 7a, under microcomputer control during the horizontal scanning sequence.

The Cephalographic patient positioning system 9 is supported on the samearm where the x-ray imager 7 is suspended and is kept steady during thescanning process.

The x-ray imager 7 can be relocated from Cephalographic to Panoramicposition and vice versa by using a telescopic arm either provided withan active actuator 12 or to be manually actuated.

In FIG. 6 b an arrangement is illustrated, where the x-ray source 11 iskept steady, while the primary x-ray collimator 5, the secondary x-raycollimator 8 and the x-ray imager 7 are synchronously moved, alignedwith the x-ray beam, by using the respective drive axis, 5 a, 8 a and 7a, under microcomputer control during the horizontal scanning sequence.

The Cephalographic patient positioning system 9 is supported on the samearm where the x-ray imager is suspended and is kept steady during thescanning process.

The x-ray imager 7 can be relocated from Cephalographic to Panoramicposition and vice versa by using a folding arm either provided with anactive actuator 12 or to be manually actuated.

In FIG. 6C an arrangement is illustrated, where the x-ray source 11 iskept steady, while the primary x-ray collimator 5, the secondary x-raycollimator 8 and the x-ray imager 7 are synchronously moved, alignedwith the x-ray beam, by using the respective drive axis, 5 a, 8 a, and 7a, under microcomputer control during the horizontal scanning sequence.

The secondary x-ray collimator 8 and the Cephalographic patientpositioning system 9 are supported on an arm rigidly connected to theframe 2. The independent actuator 8 a shall be foreseen providingmovement of the secondary collimator 8 relative to the arm.

The x-ray imager 7 can be relocated from Cephalographic to Panoramicposition and vice versa by using a telescopic arm either provided withan active actuator 12 or to be manually actuated.

In FIG. 6D an arrangement is illustrated, where the x-ray source 11 iskept steady, while the primary x-ray collimator 5, the secondary x-raycollimator 8 and the x-ray imager 7 are synchronously moved, alignedwith the x-ray beam, by using the respective drive axis, 5 a, 8 a, and 7a, under microcomputer control during the horizontal scanning sequence.

The secondary x-ray collimator 8 and the Cephalographic patientpositioning system 9 are supported on an arm rigidly connected to theframe 2. An independent actuator 8 a shall be foreseen providingmovement of the secondary collimator 8 relative to the arm.

The x-ray imager 7 is relocated from Cephalographic to Panoramicposition and vice versa by using a folding arm either provided with anactive actuator 12 or to be manually actuated.

In FIG. 7, 7 a, 7 b, 7 c arrangements are shown where the Real-TimeDigital Cephalography is implemented by a scanning movement in thevertical direction of the Z-axis, using a narrow x-ray beam and a linearshaped x-ray imager having an active area of a length approximatelycorresponding to the minimum useful width of the x-ray field size at thefilm plane used in Conventional Cephalography.

In this arrangement a software post-processing of the acquired imagewill be required to correct the magnification distortion in the Zdirection.

In FIG. 7 an arrangement is illustrated where the x-ray source 11, theprimary x-ray collimator 5, the secondary x-ray collimator 8 and thex-ray imager 7 are simultaneously and linearly moved in the verticaldirection, by acting on the Z axis under microcomputer control duringthe scanning sequence.

The Cephalographic patient positioning system 9 is rigidly connected tothe base, to the wall, or to the floor (support 14), providingindependent adjustment, either manual or motorized by the actuator 14 aof the patient height.

In FIG. 7 a an arrangement is illustrated where the x-ray source 11, theprimary x-ray collimator 5, the secondary x-ray collimator 8 and thex-ray imager 7 are simultaneously and linearly moved in the verticaldirection, by acting on the Z axis under microcomputer control duringthe scanning sequence.

The Cephalographic patient positioning system 9 is supported on the samearm where the x-ray imager is suspended, where an independent activeactuator 9 a shall be foreseen providing movement relative to thesupporting arm in opposition to the scanning movement, in order tomaintain the patient in a firm position.

In the alternative arrangements of FIG. 7 b, 7 c, the x-ray imager 7 canbe relocated from Cephalography to Panoramic Radiography, Scannographyand Linear Tomography. In this way the x-ray imager 7 takes the positionand replaces the x-ray imager 6, so achieving a remarkable reduction ofthe system cost.

The extension movement of the apparatus may be automatically triggeredand controlled by a user command or by the selection of the radiographicmodality. It shall prevent collisions with the patient positioningsystem, and shall incorporate provision for safety release to avoidpotential injury to the patient.

In FIG. 7 b an arrangement is shown, where the x-ray source 11, theprimary x-ray collimator 5, and the x-ray imager 7 are simultaneouslyand linearly moved in the vertical direction, by acting on the Z axisunder microcomputer control during the scanning sequence.

The Cephalographic patient positioning system 9 and the secondary x-raycollimator 8 are rigidly connected to the base, to the wall, or to thefloor, by a support 14, providing independent adjustment of the patientheight, either manual or motorized by the actuator 14 a.

The secondary x-ray collimator 8 is synchronously moved, aligned withthe x-ray beam, by the independent actuator 8 a under microcomputercontrol during the scanning sequence.

The x-ray imager 7 is relocated from Cephalographic to Panoramicposition and vice versa by using a telescopic arm either provided withan active actuator 12 or to be manually actuated. After relocation bythe telescopic arm, the linear shaped imager is tilted in the horizontalposition by an independent actuator 13.

In FIG. 7 c an arrangement is shown, where the x-ray source 11, theprimary x-ray collimator 5, and the x-ray imager 7 are simultaneouslyand linearly moved in the vertical direction, by acting on the Z axisunder microcomputer control during the scanning sequence.

The Cephalographic patient positioning system 9 and the secondary x-raycollimator 8 are rigidly connected to the base, to the wall, or to thefloor, by a support 14, providing independent adjustment of the patientheight, either manual or motorized by the actuator 14 a.

The secondary x-ray collimator 8 is synchronously moved, aligned withthe x-ray beam, by the independent actuator 8 a under microcomputercontrol during the scanning sequence.

The x-ray imager 7 is relocated from Cephalographic to Panoramicposition and vice versa by using a folding arm either provided with anactive actuator 12 or to be manually actuated. After relocation by thefolding arm, the linear shaped imager is tilted in the horizontalposition by an independent actuator 13.

In FIG. 8, 8 a, 8 b arrangements are shown where the Real-Time DigitalCephalography is implemented by a scanning movement in the verticaldirection (Z-direction) of the primary x-ray collimator 5, using anarrow x-ray beam and a linear shaped x-ray imager having an active areaof a length approximately corresponding to the minimum useful width ofthe x-ray field size at the film plane used in ConventionalCephalography.

In these arrangements no software post-processing of the acquired imagewill be required.

In FIG. 8 an arrangement is illustrated where the x-ray source 11 iskept steady, while the primary x-ray collimator 5, the secondary x-raycollimator 8 and the x-ray imager 7 are synchronously moved, alignedwith the x-ray beam, by using their respective actuators 5 a, 8 a, 7 aunder microcomputer control during the vertical scanning sequence.

The Cephalographic patient positioning system 9 is supported on the samearm where the x-ray imager is suspended. The arm is rigidly connected tothe frame 2.

In the alternative arrangements of FIG. 8 a, 8 b, the x-ray imager 7 canbe relocated from Cephalography to Panoramic Radiography, Scannographyand Linear Tomography. In this way the x-ray imager 7 takes the positionand replaces the x-ray imager 6, so achieving a remarkable reduction ofthe system cost.

The extension movement of the apparatus may be automatically triggeredand controlled by a user command or by the selection of the radiographicmodality. It shall prevent collisions with the patient positioningsystem, and shall incorporate provision for safety release to avoidpotential injury to the patient.

In FIG. 8 a an arrangement is illustrated, where the x-ray source 11 iskept steady, while the primary x-ray collimator 5, the secondary x-raycollimator 8 and the x-ray imager 7 are synchronously moved, alignedwith the x-ray beam, by using their respective actuators 5 a, 8 a, 7 aunder microcomputer control during the vertical scanning sequence.

The Cephalographic patient positioning system 9 and the secondary x-raycollimator 8 are rigidly connected to the base, to the wall, or to thefloor by the support 14, providing independent adjustment of the patientheight, either manual or motorized by the actuator 14 a.

The independent actuator 8 a provides movement of the secondarycollimator 8 relative to the supporting arm.

The x-ray imager 7 can be relocated from Cephalographic to Panoramicposition and vice versa by using a telescopic arm either provided withan active actuator 12 or to be manually actuated. After relocation bythe telescopic arm, the linear shaped imager is tilted in the horizontalposition by an independent actuator 13.

In FIG. 8 b an arrangement is illustrated, where the x-ray source 11 iskept steady, while the primary x-ray collimator 5, the secondary x-raycollimator 8 and the x-ray imager 7 are synchronously moved, alignedwith the x-ray beam, by using their respective actuators 5 a, 8 a, 7 aunder microcomputer control during the vertical scanning sequence.

The Cephalographic patient positioning system 9 and the secondary x-raycollimator 8 are rigidly connected to the base, to the wall, or to thefloor by the support 14, providing independent adjustment of the patientheight, either manual or motorized by the actuator 14 a.

The independent actuator 8 a provides movement of the secondarycollimator 8 relative to the supporting arm.

The x-ray imager 7 can be relocated from Cephalographic to Panoramicposition and vice versa by using a folding arm either provided with anactive actuator 12 or to be manually actuated. After relocation by thefolding arm, the linear shaped imager is tilted in the horizontalposition by an independent actuator 13.

In FIG. 9, 9 a, 9 b arrangements are shown where the Real-Time DigitalCephalography is implemented by a rotatory scanning movement of theprimary x-ray collimator 5, using a narrow x-ray beam and a linearshaped x-ray imager having an active area of a length approximatelycorresponding to half the minimum useful height of the x-ray field atthe film plane.

In these arrangements software post-processing of the acquired imagewill be required, in order to perform geometric correction of themagnification distortions.

In FIG. 9 the arrangement is illustrated where the x-ray source 11 iskept steady, while the primary x-ray collimator 5, the secondary x-raycollimator 8 and the x-ray imager 7 are synchronously moved, alignedwith the x-ray beam, by using their respective actuators 5 a, 8 a, 7 aunder microcomputer control during the rotational scanning sequence.

The Cephalographic patient positioning system 9 is supported on the samearm where the x-ray imager is suspended. The arm is rigidly connected tothe frame 2.

In the alternative arrangements of FIG. 9 a, 9 b, 9C, 9D, the x-rayimager 7 can be relocated from Cephalography to Panoramic Radiography,Scannography and Linear Tomography. In this way the x-ray imager 7 takesthe position and replaces the x-ray imager 6, so achieving a remarkablereduction of the system cost.

The extension movement of the apparatus may be automatically triggeredand controlled by a user command or by the selection of the radiographicmodality. It shall prevent collisions with the patient positioningsystem, and shall incorporate provision for safety release to avoidpotential injury to the patient.

In FIG. 9 a the arrangement is illustrated where the x-ray source 11 iskept steady, while the primary x-ray collimator 5, the secondary x-raycollimator 8 and the x-ray imager 7 are synchronously moved, alignedwith the x-ray beam, by using the respective drive axis, 5 a, 8 a and 7a, under microcomputer control during the rotational scanning sequence.

The Cephalographic patient positioning system 9 is supported on the samearm where the x-ray imager 7 is suspended and is kept steady during thescanning process.

The x-ray imager 7 can be relocated from Cephalographic to Panoramicposition and vice versa by using a telescopic arm either provided withan active actuator 12 or to be manually actuated.

In FIG. 9 b the arrangement is illustrated, where the x-ray source 11 iskept steady, while the primary x-ray collimator 5, the secondary x-raycollimator 8 and the x-ray imager 7 are synchronously moved, alignedwith the x-ray beam, by using the respective drive axis, 5 a, 8 a and 7a, under microcomputer control during the rotational scanning sequence.

The Cephalographic patient positioning system 9 is supported on the samearm where the x-ray imager is suspended and is kept steady during thescanning process.

The x-ray imager 7 can be relocated from Cephalographic to Panoramicposition and vice versa by using a folding arm either provided with anactive actuator 12 or to be manually actuated.

In FIG. 9C an arrangement is illustrated, where the x-ray source 11 iskept steady, while the primary x-ray collimator 5, the secondary x-raycollimator 8 and the x-ray imager 7 are synchronously moved, alignedwith the x-ray beam, by using the respective drive axis, 5 a, 8 a, and 7a, under microcomputer control during the rotational scanning sequence.

The secondary x-ray collimator 8 and the Cephalographic patientpositioning system 9 are supported on an arm rigidly connected to theframe 2.

The x-ray imager 7 can be relocated from Cephalographic to Panoramicposition and vice versa by using a telescopic arm either provided withan active actuator 12 or to be manually actuated.

In FIG. 9D an arrangement is illustrated, where the x-ray source 11 iskept steady, while the primary x-ray collimator 5, the secondary x-raycollimator 8 and the x-ray imager 7 are synchronously moved, alignedwith the x-ray beam, by using the respective drive axis, 5 a, 8 a, and 7a, under microcomputer control during the rotational scanning sequence.

The secondary x-ray collimator 8 and the Cephalographic patientpositioning system 9 are supported on an arm rigidly connected to theframe 2.

The x-ray imager 7 is relocated from Cephalographic to Panoramicposition and vice versa by using a folding arm either provided with anactive actuator 12 or to be manually actuated.

In FIG. 10 an arrangement is shown where a detachable connector 100allows, in a secure and ergonomic way, the manual connection anddisconnection of the x-ray imager 6 selectively between theCephalographic and the Panoramic position.

1. A dental x-ray diagnostic apparatus for performing real-time digitalradiography in Cephalography of a patient skull, the apparatuscomprising: a base frame arrangement; a rotary frame coupled to the baseframe arrangement, the rotary frame supporting an x-ray source; acinematic unit connecting the rotary frame and the base framearrangement, the cinematic unit being configured to executeroto-translational movements of the rotary frame, wherein theroto-translational movements comprise one rotation movement and twotransverse linear movements in a horizontal plane, and theroto-translational movements of the rotary frame being driven byindependent actuators in the cinematic unit controlled by data suppliedfrom a microcomputer; an x-ray imager disposed in a Cephalographicposition, the x-ray imager being movable during a scanning operation byan independent actuator; and wherein the roto-translational movements ofthe cinematic unit permit the rotary frame to perform a roto-translatingscanning trajectory to permit illumination of the patient skull by thex-ray source from a predefined virtual center of irradiation.
 2. Anapparatus as in claim 1, further comprising a second x-ray imager, thesecond x-ray imager being supported by the rotary frame and disposedopposite the x-ray source in a Panoramic position.
 3. The apparatus asset forth in claim 2 wherein the second x-ray imager has an active areaof a size approximately equivalent to a radiographic film.
 4. Theapparatus as set forth in claim 1 wherein the predefined virtual centerof irradiation is located at the focal point of the x-ray source.
 5. Theapparatus as set forth in claim 1 wherein said x-ray imager isassociated with a horizontal scanning movement, and has a linearlyshaped active area oriented vertically with a height substantiallygreater than a width.
 6. The apparatus as set forth in claim 1 whereinsaid x-ray imager is associated with a horizontal scanning movement, andis linearly translated during a scanning movement by computer control ofthe independent actuator for the x-ray imager.
 7. The apparatus as setforth in claim 1 wherein said x-ray imager is associated with a verticalscanning movement, and has a linearly shaped active area orientedhorizontally with a width substantially greater than a height.
 8. Theapparatus as set forth in claim 1 wherein said x-ray imager isassociated with a rotational scanning movement, and has a linearlyshaped active area for use with a narrow x-ray beam.
 9. The apparatus asset forth in claim 1 wherein said x-ray imager is associated with avertical, or horizontal, or rotational scanning movement, and an x-raybeam is collimated by a collimator intercepting the x-ray beam before apatient and in proximity of the patient, which is provided with anindependent active actuator capable of performing the linear orrotational translation of the collimator during a scanning movementunder computer control.
 10. The apparatus as set forth in claim 1,comprising a collimator operated by independent active actuators undermicrocomputer control, allowing resizing of an x-ray field to anydesired format required for a chosen radiographic modality as well as atranslation of the x-ray field during a vertical or horizontal orrotational scanning process.
 11. The apparatus as set forth in claim 1wherein a mechanism is given providing relocation of said x-ray imagerselectively between a Cephalographic and a Panoramic position.
 12. Theapparatus as set forth in claim 11 wherein such mechanism comprises atelescopic arm providing relocation either manually or automatically byan independent actuator under microcomputer control upon user command.13. The apparatus as set forth in claim 11 wherein such mechanismcomprises a folding arm providing relocation either manually orautomatically by an independent actuator under microcomputer controlupon user command.
 14. The apparatus as set forth in claim 11 whereinsuch mechanism comprises a detachable connector allowing in a secure andergonomic way the manual connection and disconnection of the x-rayimager selectively between the Cephalographic and the Panoramicposition.
 15. The apparatus as set forth in claim 1 wherein a patientpositioning system used in Cephalography is provided with independentactive actuators by which the patient positioning system can betranslated relative to a corresponding support frame in order tomaintain a firm patient position during a horizontal or verticalscanning process where a movement of the support frame is involved. 16.A method for operating a dental x-ray diagnostic apparatus performingreal-time digital radiography in Cephalography, comprising the steps of:positioning a patient by a patient positioning system; irradiating apatient skull from a predefined virtual center of irradiation of anx-ray source during a roto-translational movement of a rotary framesupporting the x-ray source and a linear movement of an x-ray imagerpositioned in a Cephalographic position; performing acquisition of imagedata by the x-ray imager and digital processing of the image data forreconstruction of a diagnostic image; and wherein the roto-translationalmovements of the rotary frame include one rotational movement and twotransverse linear movements in a horizontal plane, and theroto-translational movements of the rotary frame being driven byindependent actuators in the cinematic unit controlled by data suppliedfrom a microcomputer.
 17. A method for operating a dental x-raydiagnostic apparatus performing real-time digital radiography incephalography, comprising the steps of: aligning an x-ray source with anx-ray imager, either manually or automatically; positioning a patient bya patient positioning system; setting a collimator to provide a narrowx-ray beam; starting a scanning process during which the x-ray beam isrotationally translated about a horizontal axis through a patient skullby a coordinated rotational movement of the collimator and the x-rayimager under computer control, while the x-ray source is fixed inposition; and performing acquisition of image data by the x-ray imager,and computer processing for reconstruction of a diagnostic image.